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PURDUE UNIVERSITY 
PUBLICATIONS OF THE ENGINEERING DEPARTMENTS 



Vol.. in MAROH, 1919 



ELECTRIC RANGES 



BY 



C. W. PIPER 




No. 1 



BULLETIN NO. 2 
ENGINEERING EXPERIMENT STATION 



The formal organization of the Engineering Experiment Sta- 
tion of Purdue University was approved by the Board of Trustees 
on February 28, 1917. 

Its function, as set forth at that time, is to conduct researches 
in the field of engineering, to cooperate with engineering societies 
in pursuing industrial investigations; and to publish and distribute 
the results of its work in the form of bulletins. 

The board of management consists of the dean and official 
heads of the four engineering schools, the dean acting as director. 

Bulletins will be issued from time to time setting forth the 
results of scientific investigations conducted in the laboratories of 
the university by members of the station staff. 

Circulars of information, containing compilations of facts and 
data gathered from reliable sources will be published as occasion 
demands. 

The cooperation of engineering societies, of public commissions 
and of individual manufacturers in research of general interest, 
will be welcomed by the board of management. 

All communications should be addressed to 
DIRECTOR OF ENGINEERING EXPERIMENT STATION 
Purdue University, Lafayette, Indiana. 



BULLETIN NO. 2 

ENGINEERING EXPERIMENT STATION 



ELECTRIC RANGES 



BY 



C^ W. PIPER, 

Instructor in Electrical Engineering 



PURDUE UNIVERSITY 

LAFAYETTE, INDIANA 

MARCH, 1919 



1 



CONTENTS 



Page 
List of Figures 3 

Preface 4 

Introduction 5 

Electric Ranges 9 

Electric Oven Tests 9 

Results of Oven Tests 13 

Baking Tests 16 

Results of Baking Tests 17 

Miscellaneous Observations 22 

Surface Burners 22 

The Relative Cost of Baking ' 28 

Electric Range Data „. 30 

The Advantages of Electric Ranges 33 

Points to be considered in selecting an Electric Range 35 

Description of Ranges , 37 

Conclusions 40 

Index ; 41 



LIST OF FIGURES 

No. Page 

1 Range No. i. Open type heating units 6 

2 Range No. 2. Surface burners, porcelain type. Oven heat- 

ing units, open type y 

3 Range No. 3. Surface burners, enclosed type. Oven heat- 

ing units, open type 8 

4 Oven preheating and cooling curves, empty 9 

5 Oven cooling curves, oven empty 10 

6 Oven preheating and cooling curves, oven full 11 

7 Open-door characteristic, oven No. 3 12 

8 Open door characteristic, oven No. 6 12 

9 Oven preheating and cooling with temperature indicator 

curve 14 

ID Oven radiation 1 5 

1 1 Oven radiation 16 

12 Biscuit baking test 18 

13 Biscuit baking test 18 

14 Cake baking test 19 

15 Cake baking test 19 

16 Bread baking test 20 

17 Bread baking test 20 

18 Meat cooking test 21 

19 Meat cooking test 21 

20 Porcelain type surface burners 23 

21 Hot plate tests 23 

22 Open coil reflector type surface burner 24 

23 Hot plate efificiencies 25 

24 Hot plate efficiencies '. 26 

25 Semi-enclosed type surface burner 27 

26 Enclosed type surface burners 28 

2^ Comparative costs of operating ranges 30 

28 Daily load curve — Monday 32 

29 Daily load curve — Wednesday 33 

30 Range No. 4. Surface burners, porcelain type. Oven heat- 

ing units, enclosed and open type 34 

31 Range No. 5. Heating units, enclosed type 36 

32 Range No. 6. Surface burners, porcelain type. Oven heat- 

ing units, porcelain and open type 37 

33 Range No. 7. Surface burners, semi-enclosed type. Oven 

heating units, enclosed and open type 39' 



PREFACE 



The object of this bulletin is to present the characteristics of 
the different types of electric ranges, also data on the cost of baking 
with electricity. 

The work was conducted by Mr. C. W. Piper, Instructor in 
Electrical Engineering, and Mr. H. W. Asire, Research Assistant, 
Engineering Experiment Station, under the direction of Professor 
C. Francis Harding, Head of the School of Electrical Engineering, 
Purdue University. 

The Home Economics Department, under the direction of Pro- 
fessor Mary L. Matthews, co-operated extensively in the opera- 
tion of the ranges and offered valuable assistance and advice in 
connection with the cooking tests. The following students assisted 
at different times with the work as a part of their theses : Miss 
Helen Virginia Hendey, Messrs. R. B. Stein, E. W. Tatman, E. H. 
Crosby, J. M. Naylor and K. A. Rarick. 

The work was made possible through the courtesy of the Hot- 
point Electric Heating Company, Ontario, Cal. ; Rutenber Electric 
Company, Marion, Ind. ; Standard Electric Stove Company, Toledo, 
Ohio ; Hughes Electric Heating Company, Chicago, 111. ; Estate 
Stove and Range Company, Hamilton, Ohio ; Westinghouse Electric 
& Manufacturing Company, East Pittsburg, Pa., and the Globe Stove 
and Range Company, Kokomo, Ind. 



ELECTRIC RANGES 



INTRODUCTION 

The year 1890 or 1891 may be taken as the date which marks 
the first practical attempt to make electrically heated cooking ap- 
paratus. In the early days there were many technical difficulties 
to be surmounted by the pioneers in electric cooking but these have 
been gradually overcome. 

In 1891, Mr. H. J. Downing, one of the pioneers and founders 
of the Downing Radiant Heat Company, exhibited electric cookers 
and heaters, at the Crystal Palace Electrical Exhibition. 

In 1895, Col. R. E. Crompton read a paper before the Society 
of Arts on the use of electricity for cooking purposes. He also 
showed a large variety of cooking appliances and their uses. 

The American engineer and manufacturer have made rapid 
advances and contributed many valuable ideas in the electric cook- 
ing field, from as early as 1896. 

Mr. A. F. Berry placed on the British market, in 1908, the 
"Tricity" cooker. The design was quite similar to the oven of to- 
day. Many thousands of these cookers are now in daily service 
and are generally giving satisfaction. 

The progress of electric cooking in America has been retarded 
for several reasons, chief of them being the high cost of the ap- 
paratus and of the energy. However, the advantages of cooking 
with electricity are fast being recognized. 

There are now on the American market many types of electric 
cooking apparatus, some quite novel in conception and design. Com- 
plete equipments for electric cooking have been placed and are now 
in use in hotels, hospitals, colleges, convents, schools, club buildings, 
restaurants and other large establishments in America, England, 
Canada, Australia and other countries. Railways, large steamships 
and war vessels are using electricity for cooking as well as for 
lighting and motor power. 

Each step from cooking by the open fireplace, to the coal stove, 
gas and electric range has been marked by the use of more expen- 
sive fuel, greater heat efificiency. better temperature control, and 
more satisfactory food. 



There are three reasons for cooking food : 

1. To make it more digestible. 

2. To improve its appearance and flavor. 

3. To sterilize it and so arrest or prevent chemical change. 

Usually all three results are attained as in baking bread, w^here 
the raw starch is cooked to a more digestible form, the yeast plant 
is killed, preventing the bread from spoiling and the attractiveness 
is increased manv fold. 




Fig. 1. Range No. 1. Open type heating units. 

The electric fireless cooker range is well adapted for obtaining 
the above results. It has close temperature control which makes 
slow, thorough baking possible and produces more digestible food. 
A quick rise in temperature provided at will gives a nice even 
brown in a few minutes. 



The use of electricity for cooking will become even more popu- 
lar as the cost of energy is reduced. ' The energy rates throughout 
the country are in general so high that electric cooking is possible 
only to those who can afford luxuries, and until the rates are re- 
duced for cooking purposes, electrically heated stoves will be barrefl 
for the kitchen of the average family. 











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Fig. 2 Range No. 3. Surface burners, porcelain type. Oven heating units, open type. 

It has been found that at three cents per kilowatt-hour the 
housewife who operates a modern electric range can cook as eco- 
nomically as one who uses a gas range and pays one dollar per thou- 
sand cubic feet of gas. In analyzing the prices at which current is 
offered for electric cooking in the United States, the interesting fact 



is revealed that in the Eastern and Western States, the rates average 
less than four cents per kilowatt-hour, while in some central locali- 
ties where water power is available or coal is cheap, energy is sup- 
plied for as low as two cents per kilowatt-hour. 




Fig. 3. Range No. 3. Surface burners, enclosed type. Oven heating units, open type. 

The comparison and conclusions drawn in this bulletin are 
based upon the rate of three cents per kilowatt-hour which is the 
flat rate advised by the National Electric Light Association. 



9 
THE ELECTRIC RANGES 

The ranges used for this investigation were : 

Globe Electric Range Serial No. Ei 

Westinghouse Electric Range Style No. 240603 

Estate Electric Range No. 84 

Hughes Electric Range Style No. 50 

Standard Electrie Range Model No. 601 

Hot Point Electric Range Model D 

Rutenber Electric Range No. 1058 

The order in which these ranges are given above has nothing 
to do with the numbers by which they are referred to later. 

These stoves represent the best types of modern American 
electric ranges. All are of the cabinet design, except range No. 7, 




OVENS 
PREhE^TINC, AND Coolltte, 

ttApry 



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Fig. 4 

which has its oven below the surface elements. The detailed des- 
cription of the ranges will be found at the end of the bulletin. 

ELECTRIC OVEN TESTS 

The ranges were tested under conditions such as are found in 
the home, except, that rated voltage was impressed upon each range 



10 



and kept constant while in the home the voltage is somewhat var- 
iable. 

The temperatures of the ovens were measured by calibrated 
copper-advance thermocouples, and milli-voltmeters. The thermo- 
couples were placed as near the center of the ovens as conditions 
would permit. 

The tests were divided into six classes as follows: 

1. Preheating and cooling with ovens empty. 

2. Preheating and cooling with three pounds of water in 



each oven. 

3- 

4- 

5- 



Temperature indicator calibration. 
Open door test. 
Oven insulation tests. 
Baking tests. 









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Of the various tests the preheating and cooling tests with empty 
ovens will be first considered as they determine the time and energy 



II 



required to bring the ovens up to baking temperatures. These 
were made by supplying maximum current input to the empty oven. 
When the temperature reached 500° F. the current was turned off 
and the oven allowed to cool at its natural rate. Power input in 
watts and temperature readings were observed at five minute inter- 
vals. 

Curves of these tests will be found in Figs. 4, 5, and 9. 

The tests with water in the ovens were made by placing a wide 
top pan containing three pounds of cold water in the cold oven and 
heating until the water boiled. These tests were made to determine 
the time and energy required to heat the ovens when baking starts at 
room temperature. Two thermocouples were used in each oven. 
One measured the oven temperature and the other that of the 
water. The placing of water in the oven tended naturally to in- 
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While conducting the preheating tests, the performance of the 
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The temperature decrease and consequent loss of energy due to 
opening the oven doors, for short periods, was determined. The 
ovens were brought up to the desired temperature and at inter- 
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three quarters of a minute. All readings were taken at the time 
of opening and closing the doors. During the entire test the power 
input in watts was maintained constant. Figs. 7 and 8 show the 
cooling effect of open oven doors. 

The heat insulation property of the oven walls, was obtained 
by adjusting the power supplied to the oven to a definite value and 
allowing the oven temperature to rise until it became constant. The 
time required for this varied from ij^ to 7 hours. Fig. 10 shows 
the radiation from each oven throughout its working temperature 
range. 

RESULTS OF OVEN TESTS 

Preheating (ovens empty) : The energy input during the pre- 
heating run was a maximum for each oven except No. 5. This 
range was run on medium, so as to have the watts input approxi- 
mately the same as the other ovens. This caused its preheating 
time to be increased. 

It will be noted that Range No. 3 with its small oven and 
large heating units became hot the quickest, reaching 500°F. in 
nine minutes. Range No. 5 which has a heavy steel lining, heated 
most slowly. However, credited to this range is a slow cooling 
rate, while No. 3 cooled most quickly. 

The cooling rates taken from the previous tests are shown on 
Fig 5. Here it is noted that range No. 6 was the slowest to cool. 
The general oven dimensions and appearance would not indicate 
that its cooling rate should be superior to all others. 

Preheating (ovens filled): The eft'ects produced by water in 
the ovens were quite noticeable (Fig. 6). In three instances it- 
altered the position of the curves. Peaks of the curves for ovens 
No. I and No. 3 were shifted toward the others. The general ten- 
dency seemed to be to group the curves more closely, only par- 
tially overcoming, however, the domiijant oven characteristics. 

Open Door : The characteristic curves for opening doors 
show that oven No. 3 cooled quickly. During the three quarter 
minute of open door, an average temperature decrease of 75°F. oc- 
curred. In the following two minutes, when the door was closed 
the temperature increased 50°F., there being 25° net loss in tem- 
perature. Oven No. 4 corresponds very closely to that of No. 3, the 
total drop for the test being 7o°F. Ranges No. 5 and No. 6 main- 
tained a constant heat, even though their temperature was about 
100° higher than No. 3, that is, the two minute period during which 
the doors were closed, was sufficient to allow the oven to recover 
the heat lost, while the doors were open. 

The ovens lined with heavy material cool more slowly, when 
the doors are open, than the small ovens constructed of lighter 
weight material. 



14 

Temperature Indicator: The oven temperature indicators 
have a tendency to lag behind the oven temperature changes. Fig. 9 
shows a characteristic indicator temperature curve. They register 
less than the true oven temperature because the oven door tem- 
perature is lower than the temperature of the air inside the oven. 

The most satisfactory indicator tested was that on range No. 7, 
which followed closely the oven temperature changes. Its calibra- 
tion closely approximated actual tempera^tures expressed in de- 
grees Fahrenheit. 









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Oven Insulation : Ranges No. i and No. 4 required the great- 
est amount of energy while range No. 6 consumed the least. The 
other ranges consumed about the same amount of energy. 

The oven of range No. i has thin walls and a poorly fitting 
door, and the losses are great through the thin non-insulated bottom 
to the warmer oven. 

The oven of range No. 4 is large, but the reason for the loss 
of heat in this oven could not be determined by inspection. The door 
catch was of poor design and possibly the heat insulating material 
of the walls was not of the bqst quality. 

The construction of the oven of range No. 3, with the glass 
door, would indicate high losses but due to its small size, and large 
heating units, the temperature increased rapidly. 



15 

The excellent heat retaining property of oven No. 6 is prob- 
ably accounted for by the oven walls being well insulated and the 
door fitting close, as the ventilation permitted very little heat to 
escape. 

In the determination of the efficiency of the oven the volume 
must be considered as well as its temperature. The curves in Fig. 
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ordinates are derived by dividing the watts input by the volume of 
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The other ranges fall in order as indicated by the cooling rates pre- 
viously discussed. 



i6 



BAKING TESTS 



The foods chosen were those consumed regularly in the home. 
They were selected ^yith respect to the time required for baking. 
Biscuits require but a short time, bread and cake bake in about an 
hour, while meat consumes several hours.. 



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The same perspn prepared the biscuits, cake, bread and meat, 
attended to their insertion and removal f roni the ovens and inspected 
their progress during baking. This method allowed those conduct- 
ing the test to devote their entire time and attention to the many 
necessary instrument observations, and made for uniformity of 
manipulation. 



17 

BISCUITS 

The biscuits were baked in the ovens at an approximate tem- 
perature of 45o°F. Observations were recorded at intervals of two 
minutes. The baking extended over a period of ten to twelve min- 
utes. 

One batch of dough was prepared, from which a pan of six 
biscuits was placed in each oven. This made, the tests uniform and a 
comparison of results possible. Five tests were conducted in each 
oven. 

CAKE 

Three cake bakings were run in each oven, each cake taking 
about sixty minutes at an approximate temperature of 35o°F. 

BREAD 

The bread baking was conducted in a similar manner to the 
foregoing tests, one batch of dough being prepared from which an 
equal amount was placed in each oven. The bread was in the oven 
for approximately seventy-five minutes, at a temperature of 375 °F. 

MEAT 

One meat roasting test was conducted in each oven. The roast 
was started at a temperature of approximately 475 °F. During the 
three hours required to prepare the meat, the temperature was al- 
lowed to decrease to about 300° F. 

RESULTS OF BAKING TESTS 

The results of the baking tests are given in Figs. 12 to 19. The 
continuous curves are for the oven temperature. Any adjustment 
of the control switch, or opening and closing of the oven door 
causes a lagging increase or decrease of the oven temperature ; hence 
a gradual rise or fall in the temperature curve. The oven tem- 
perature for the bread and meat should decrease slowly as baking 
progresses as indicated in the curves. 

The adjustment of the control switch produces an immediate in- 
crease or decrease of the power input, which is represented by the 
dotted line and accounts for its irregularity. When the oven is 
being used as a fireless cooker the power is turned off. During the 
baking some of the ovens require a large amount of power, while 
others use very little and often were operated as fireless cookers. 
Range No. 5 was operated as a fireless cooker most of the time. 

The first test was started at the point marked "No. i in" and 
baking continued until the point marked "No. i out." The second 
test was prepared and started at the point marked "No. 2 in," thus 
the baking continued throughout the tests. 











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/ 
















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Fig. 13 









1.2 600 

H 

Z 
10 ^ 500 

X 

if 

> ^ 




































































5 — 


Biscuit Baking Test 
Oven No 3 














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t ^ 
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> IOZO3O4O9D«07D8O00lC 
TiMt IM HlHUTtS 


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Fig. 13 



19 



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Cake Bakin6 Test 
J OvtN No. Z 










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ZA 600 

b 

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Cake Bakins Te3T 
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> -S 1.0 1.6 £.0 IS 3.0 t.5 

Time in Hours 





Fig. 15 



20 









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C It 

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Bread Baking Test 
Oven No 4- 








— 


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o 


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"■ "a 5 1.0 1.5 ZO Z5 3.0 3 5 40 
TiMEL IN Hours 



Fig. 16 







































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Bread Baking Test 
Oven No. 5 










24 600 

1- 

X 

ao J 500 

X 






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21 











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Meat Cookins TtsT 
Oven No 2 






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5 5 1.0 I.S Z.O 

Time in Hours 


2.5 _3.0 a5 



rig. 18 







24 6oo 

)- 

Z.O 1 500 

u 
c 

a 

if 

^ 1.6 ^ 400 

O ac 

ID Q 

f f 

f i 

f .8 S! 200 





- 1 






























































Meat Cooking Test 
Oven No. 6 








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1 
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1 








C 


5 10 1.5 2.0 2.5 3.0 3. 
Time in Hours 


s 



Fig. 19 



22 

MISCELLANEOUS OBSERVATIONS 

The method of operating the ranges was similar in every case. 

Individual taste, difference in ovens and variation in voltage 

; of the supply circuit, all tend to produce a variable time temperature 

i curve. Thus the curves given for the time and temperature of bak- 

' ing Figs 12 to 19 are only suggestive. 

Ovens No. i and No. 2 required more heat than the others. It 
was probably because their radiation was great and their loss of heat 
large when doors were opened. It did not increase the cost of operat- 
ing materially, as it takes a very short time to get the ovens hot. 

The oven of range No. 3 was just large enough for the small size 

roaster, and so shallow that the bread almost touched the top coil. 

i When roasting meat, this was the only oven in which steam con- 

' densed and ran out around the door. This condensing might have 

been caused by the cool glass in the oven door. 

In oven No. 4 the food had to be turned so as to brown evenly, 
probably because of improper location of the heating coils. 

Oven No. 5 was steam tight and held heat longest, but upon 
opening the oven door, the fumes of the fat from the roasting meat, 
and the intense heat were very disagreeable to the face and eyes. 
The flavor of the meat roasted in this oven was not nearly as good 
as the other roasts, due to the tight oven, not permitting the vapor to 
escape. 

The ovens after being heated, did not need both the upper and 

i lower coils energized, the lower coil only being used most of the 

1 time. The upper coil was used only when baking was nearly com- 

i plete. so as to give the desired brown to the food. 

j During most of the baking operations, the ovens could have 

' been operated partially as fireless cookers. They are so constructed 

■ as to economize in power in that way. The current also might have 

been turned off a few minutes before the food was entirely cooked 

and finished as in a fireless cooker. The better one understands the 

ranges, the more economical will their operation become. 

i SURFACE BURNERS 

I 

I Four types of surface burners were studied. 

• Ranges Nos. 2, 4 and 6, were equipped with moulded porcelain 

I burners. These are round flat porcelain plates with deep grooves in 
their upper surfaces to receive the heating coils. This type of burn- 
i er transfers the heat more by conduction than by radiation. 
' The open coil reflector burner on Range No. i has the coils 

i mounted in a steel frame, supported with porcelain bushings in 
truss construction. A bright reflector is located underneath to as- 
sist in concentrating the heat upon the cooking utensils. The heat 
is transferred to the vessel principally by radiation and convection. 



2.^ 




Fig. 21). Porcelain type surface burners. 









too 

h 














































































-^ 




-^ 


T^ 






^ 








p3 


5=- 
























/ 


/' 




/ 


y' 






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y 


/ 






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/^ 


X' 






















Jf 




\0, 


/ 








y 




A 


u 


X 


,/ 


/ 












X 

c 
I 

^ (60 

UJ 

u 

(t 

(* 

u 

Q /40 
2 
lU 

f 

c 

t" (DO 

5 
1 

SO 














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/ 


/ 


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/ 


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Hot PcATt TtsTa 

3 L«& Vl^TtR Ht/«TtP TO 

BoH-irtO & E.VA(»o««TtD. 


















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y 


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y 


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5 lo IS t^ e.5 

T/MC IN Minutes 





Fig. 21 



The semi-enclosed unit of range No. 7 is of the moulded porce- 
lain construction. The element is separated from the vessel by a 
cast steel grating. Heat must be carried largely by convection for 
about three quarters of an inch to the grating, then by conduction to 
the utensil. 



24 

The enclosed or iron-clad unit has its coils entirely within a 
steel jacket, which presents a smooth surface to the vessel. Ranges 
Nos. 3 and 5 have this type of surface burner. They are very 
efficient with metal ware, as the heat is transferred directly by 
conduction. 




Fig. 22. Open coil reflector type surface burner. 

SURFACE BURNER TESTS 

The tests were conducted under laboratory conditions such as 
constant voltage and the elimination of cool air currents from the 
room. A known amount of water was evaporated and the input 
noted. A vessel was selected that would just cover the hot plate. 
This was a dark granite straight side pan, eight inches in diameter 
and six inches high, with a bulge upward in the bottom, of about 
three-eighths of an inch. Three pounds of water were used in each 
test and evaporated down to the ton of the bulge. The weight of the 
remaining water, subtracted from the three pounds,- gave the amount 
evaporated. The change of temperature was noted at five-minute 
intervals up to the boiling point. The temperature increased rapidly 
to 205°F. and very slowly from this point to 2i2°F, It was difficult 
to determine the exact time that the water arrived at the boiling 
point. Due to this fact no calculations have been made involving 
the boiling point. Efficiencies have been calculated for the total boil- 



25 

ing period and for the first eight minutes of the heating period. Fig. 
21 shows the time required to heat three pounds of water to the boil- 
ing point on each of the seven ranges. 

The thermal efficiency was obtained by comparing the British 
thermal units absorbed by the water, with the British thermal units 
put into the burner. 

The following relations are stated in order that the method of 
determining the thermal efficiencies may be evident. 







Hot Plate, EFFicieNciE.s 

BY 

ElVAPORATlON OF WaTER 








a 




9 


< 




Z Z Z (T 


VO ^ 

1 1 

> t^ u 

'. z -^ 


) 




1 . - ^ 


i 










1 1 



















































































30 



Fig. 33 

To raise the temperature of one pound of water one degree 
Fahrenheit, one British thermal unit is required. 

To evaporate one pound of water at 2i2°F. requires the absorp- 
tion of 969.7 British thermal units. 

One kilo-watt-hour is equivalent to 3415 British thermal units. 

The efficiencies as shown in Fig. 23, were obtained by adding to 
the product of the temperature change and total weight of water, the 
British thermal units obtained by the product of 969.7 and the weig'ht 
of water evaporated, expressed in pounds. This sum was then divid- 
ed by 3.415 times the watt hours used. 



26 

T == Temperature of water at start of test. 

T' = Temperature of water at end of test. 

W = Total weight of water in pounds. 

W' = Total weight of water evaporated in pounds. 

WH = Watt hours put into the burner. 



(T— T) W + 969.7 \\" 
3.415 (W.H.) 



= Efficiency 



The efficiency at the end of the first eight minutes, at a point 
below the boiling temperature on each range, was obtained in a simi- 
lar manner. Fig. 24 shows the hot plate efi^iciencies for three pounds 
of water heated for eight minutes. 



100 

90 
&0 



O 60 

u 

Oi. 50 











3 L 


Hot Plate ELpncieNaes 
-bsl Watelr Heated for 
& Minutes 












\c 


5 ^° 

't r- 

d ^ 
Z c 


Q 




c 


1 








2 








1 


t 

- c 


0^ 
- in 


^ n 








c 
2 


I 5 


CO 

1 








■ 


d 














^ 










1 



4.0 



Fig. 24 



THE BURNERS 

The grooves of the moulded porcelain burner form deep pockets 
in which the food lodges. This has to be burned or' dug out to pre- 
vent the burner from becoming hot in spots and being damaged. 

The open-coil reflector burner, to maintain its high efficiency 
depends upon the reflector being kept brig'ht. Particles of food drop 
through and lodge upon the reflector. This, together with the intense 
heat, cause a loss of reflecting properties which lowers the efficiency 
rapidly. 



^7 

The semi-enclosed burner is very difficult to keep clean. 

The enclosed burner is expensive to operate for short periods 
and takes more time and energy for heating. 

The radiant reflector type is most efficient in the laboratory 
where conditions are under better control and where the reflector can 




Fig. 2.5. Semi-enclosed type surface burner. 



be kept bright by frequent changes. With burners such as this in the 
home, the efficiency might soon drop below that of the porcelain type. 

The porcelain burner maintains a high efficiency without much 
attention. 

For long periods of heating the iron-clad and semi-enclosed 
units are best adapted and are very efficient. 



28 

THE RELATIVE COST OF BAKING 

The following tables give the results of the various tests upon 
the seven electric ovens. The three cent kilowatt-hour rate was 
used in computing the costs. 




l"ig. 2'>, EiK'losed type surface liurners. 









BISCUITS 


ove 


Preheating 


Preheating 


Number of 


lo. 


watt hours 


time min. 


tests 


I 


558 


15 


4 


2 


547 


12 


4 


3 


891 


50 


3 


4 


929 


20 


4 


5 


1677 


38 


5 


6 


1075 


21 


5 


7 


961 


25 


4 



V. H. to Percent Total Total 
bake of total w.h.pre- cost 
w. h. to heating cents 
bake & baking 



178 


24 


736 


2.2 


194 


26 


741 


2.27 


128 


12 


1019 


3-0 


III 


10 


1040 


3-1 


150 


8 


1827 


5-4 


116 


9 


1191 


3-5 


137 


12 


1098 


3-3 



Oven No. i cost less for biscuits, while No. 5 proved to be 
the most expensive. The heating units in oven No. i were of the 
open type and the ventilated oven was lined with bright aluminum. 
The heat units of No. 5 were of the enclosed type, imbeded in heavy 
cast steel. The oven was lined as No. i but was not ventilated. 

Biscuit baking is a short process, requiring but twelve minutes. 
It is evident that ovens constructed as that of No. i with the open 
type heating unit are the most economical for short period baking, 
owing to their quick preheating characteristic. 







29 












CAKE 








stove Preheating 


Number 


Watt-hours 


Percent of 


Total watt 


Total 


No. watt hours 


of tests 


to bake 


total w.h. 


hours preheat- 


cost 








to bake 


ing & baking 


cents 


I 558 


3 


885 


61 


1443 


4-3 


2 547 


3 


356 


39 


903 


2.7 


3 891 


3 


322 


24 


1303 


3-9 


4 929 


3 


458 


33 


1387 


4-1 


5 1677 


4 


326 


16 


2004 


6.0 


6 1075 


4 


360 


25 


1435 


4-3 


7 961 


3 


412 


30 


1375 


4.1 


Oven No. 2 


was a 


little cheaper for 


cake baking 


than 


oven No. i. Thei 


r construction is similar. Oven No. K was 


again 



the most expensive. 









BREAD 






Stove 


Preheating 


Watt hours 


Percent total 


Total watt 


Total cost 


No. 


watt hours 


to bake 


w.h. to bake 


hours preheat- 
ing & baking 


cents 


I 


558 


576 


51 


1 134 


3-4 


2 


547 


346 


35 


893 


2.6 


3 


891 


362 


39 


1253 


3-7 


4 


929 


591 


39 


1520 


4-5 


5 


1677 


32 


2 


1710 


S-i 


6 


1075 


288 


21 


1363 


4.0 


7 


961 


423 


30 


1384 


4-1 



Three bread baking tests were run in each oven. They were 
similar to those of the cake. The time required was about the same 
in both cases, being seventy-five or eighty minutes. The small 
input for bakin, to oven No. 5 was due it its use as a fireless oven 
most of the time. 

MEAT 



Stove Preheating 


Watt hours 


Percent total 


Total watt Total cost 


No. 


watt hours 


to bake 


w.h. to bake 


hours preheat- 
ing & "baking 


cents 


I 


558 


2224 


81 


2782 




8.3 


2 


547 


1315 


71 


1862 




5-5 


3 


891 


1 169 


57 


2060 




6.1 


4 


939 


1299 


58 


2228 




6.6 


5 


1677 


499 


23 


2177 




6.5 


6 


1075 


143 


12 


1218 




3-6 


7 


961 


1974 


67 


2935 




8.8 




The longer 


baking tests. 


such as with the 


meat, 


rather 


reverse the conclusions derived from the short tests. 


Oven 


I No. I 



was best for short baking periods, while it was about the most ex- 
pensive for cooking of long duration. The heavy enclosed type of 



30 

heating unit and ovens of the type of No. 5 were found to be the 
cheapest for long periods of baking. They are the most expensive 
for quick baking. 

The comparative costs of operating the electric ranges are given 
in Fig. 2^/. 

The energy required to preheat the ovens is large as compared 
with that put into the ovens for baking. Thus the quantity of food 
could be increased for larger families without the same proportion- 
ate increase in cost. 







CoHPAnATivt Cost 
or 

OPtWATIMG rtANaC 


* MtAT 




- N ■< ifl IB h- 
& bbooaod 

i X z X X X X 








DISCU1T6 


CAKt 

- N « ■« wi « 1 
( b « b b 6 

'. 1. t X i X -i 


5HE.AO 






- w ifl ^ in « r- 

it <i <> i 6 6 

. 7 z "» 7 ;■ ■* ■» 


3 

r 


- to »i < m i» t 


i 


_ 




































































































1 1 











































































































































































o 

X 9 



Fig. 27 

An oven selected for the home should be one suitable for short 
baking periods as with few exceptions food prepared in the home 
requires less than oue hour for baking. It should have a well insu- 
lated, light aluminum lining and adjustable ventilation. Open type 
heating units are most desirable. 

Service such as restaurants, hotels, clubs, etc., where the ovens 
will be in service for long periods and quite frequently, the heavy 
cast steel enclosed, heating unit would be by far the most -economical. 

ELECTRIC RANGE DATA 

The cost of operating the electric range in the home, together 
with the characteristic range load curve, have been studied by sev- 
eral of the large power companies, so as to make the proper adjust- 
ment of energy rates. ■ 



31 

Mr. Henry Wallsmith, Hartford City, Indiana, in his report* 
to the American Gas & Electric Company, shows some very inter- 
esting facts in regard to electric range performance for different size 
families and homes. 

The rate paid for electricity is a combination cooking and 
lighting rate ; lighting rate eleven cents per K. W. H., cooking rate 
six cents per first ten K. W. H., and all excess consumption three 
cents per K. W. H. 



Size of Number of Time Range Light Total Total Net Range 

family rooms month & day k.w.h. k.w.h. k.w.h. bill bill 



2 


6 


I-I4 to 2-21 


36 


II 


47 


$2.29 


$1.19 


2 


■ 6 


3-24 to 4-24 


71 


II 


82 


3.26 


2.16 


3 


7 


1-22 to 2-21 


112 


20 


132 


5.06 


3.06 


5 


6 


3-22 to 4-22 


54 


58 


112 


4.24 


1.56 


5 


8 


2-23 to 3-24 


lOI 


z^ 


133 


5-31 


2. II 


7 


lO 


2-21 to 3-21 


108 


51 


159 


6.53 


1.43 


7 


10 


12-22 to 1-22 


167 


57 


218 


8.30 


2.60 



The Pacific Power & Light Company reports'' a detailed inves- 
tigation into the cost of cooking by electricity. The results obtained 
from the investigation indicate that the average family can cook 
electrically for about $3.00 per month with energy selling at 3.6 cents 
per K. W. H. The company has a total of 201 electric ranges con- 
nected to its lines. 

The average monthly number of ranges in service was 161, 
with a yearly cost for operating each range of $30.60. The average 
monthly bill was $2.55 net. The company has deducted from the 
total, all the minimum charge bills and their earnings and finds that 
the average bill now is $3.13 a month. This is a more accurate ex- 
pression of the cost of electric cooking, because the minimum 
charge bills do not indicate that the ranges were really used to their 
best advantage. 

A New England Power Company which has sixty ranges con- 
nected to its lines, and a rate of three cents per K. W. H., reports* 
an average cost of eighty cents per month per person as a fair cost 
of preparing meals electrically. 

The cost of baking electrically as presented by this bulletin 
can not be stated in terms of cost per person per month as this in- 
cludes cooking with both surface burners and ovens. 



* N. E. L. A. Bulletin 

t Electrical World. Januarv. 1919 

t N. E. L. A. Bulletin 



32 

CHARACTERISTICS OF RANGE LOAD 

The opinion of many engineers is that the peak of the range 
load occurs at the same time as the station peak and that the maxi- 
mum range demand will be a large percentage of the range con- 
nected load. Mr. R. B. Snyder of the Milwaukee Electric Rail- 
way & Light Company, in his analysis of the electric range load 
found several conditions which are interesting to note.* 

The demands upon the gas supply for the average city, where 
most of the homes use this fuel for cooking, occurs at the noon 
hour. These are the consumers who will eventually use electricity, 
so their maximum demand will no doubt be at the same hour. 









to 
































15 
«) 

1" 

O 
J 

i s 








Daiuy Load Curve. 
Monday 


























/ 


i 




























\ 


































k 




























A 








r\ 




















M- 


A 




/ 


r^ 


u 








J 


\ 




\ 


_jL 


\ 


^ 


/ 




A 








r 


H 




\ 


4 


» a K) 12 2 4- 6 £ 
A.M. (nooh) P.m. 


J 



Fig. 28 4 

The demand from the apartment buildings seems to be of a 
different character. The average daily load for an apartment with 
twenty-two electric ranges in service, gives the curves of Figs. Nos. 
28 and 29 with the peak in the evening from 5 p. m. to 6:30 p. m. 

The distribution of electric ranges between ordinary homes 
and apartment buildings results in a distinct advantage to the com- 
pany furnishing the power supply. With the range load thus divided, 
two peaks occur in the range load curve, instead of a single one. 
These peaks appear at from 11 :30 A. M. to i :oo P. M., and from 
5:00 P. M. to 6:30 P. M. 



Electrical World, April 14, 1917 



33 

The curves indicate further that the demands for each week day 
was about the same. The maximum was 22 K. W., with Sunday 
a minimum of 9 K. W. The total connected load was 98 K. W. 
The maximum demand for a group of twenty-five ranges will not 
exceed fifteen percent of the connected load. The maximum de- 
mand for a single range may averge 40 to 60 percent of its rating. 

The average daily consumption per person over a period of ten 
days was 1.18 K. W. H., including lights. This shows the average 
consumption to be well below i K. W. H. per person per day. 











zo 

15 



J 

2 

s 








































Daiuy Load CuRVt 

WtONCSDAY 




















































r 




























f 
















A 


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\ 








1 




















\ 






f 












/ 








f 


'\ 


^ 




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^A 






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°< 


& 8 K> *Z 2 
A.M. {.r*o<m\ 


4^ e t 
P.M. 


) 



Fig. 29 



THE ADVANTAGES OF ELECTRIC RANGES 

The possibilities of using electricity extensively for cooking 
purposes are rapidly being recognized in all parts of the country. 

The gas stove is gradually being replaced by the electric range. 
This replacement will continue unless a gas stove can be produced 
which will duplicate the results obtainable with the electric range. 

Undoubtedly the electric range will maintain its superiority. It 
will do that which the ordinary gas range will do and in addition is 
more sanitary and does better cooking, due to the fact that there 
is less shrinkage. Edibles do not become dried out as in the gas 
range and the results are more like the coal range. 



34 

Gas is more generally used in the cooking field today solely 
because it is at present cheaper than electricity. However, electricity 
is constantly becoming cheaper, and has reached such a figure in 
many parts of the country that many electric stove companies are 
earning good dividends. 

There can be YtP question about the advantages of electricity 
over gas or coal, for heating and cooking purposes. It is convenient. 
All that is necessary to start the cooking operation is to snap a switch 
or press a button. It is cleanly, it causes no smoke, soot, noxious 
gas, ashes or dirt. It is labor saving in that it eliminates dirt from 
pots and pans. It is safe in that there is no danger of fire from 




Fig. 30. Range No. 4. Surface burners, i>orcelain type, 
enclosed and open t.vpe. 



Oven heating vmits. 



gases. It can be easily regulated to produce a steady even heat at 
any desired temperature, by the upper and lower heating units 
having three controls each, giving eighteen different oven temper- 
atures. 

The automatic attachments which can be placed upon electric 
ranges are desirable as well as economical. The clock, thermastat, 



35 

and fireless cooker arrangement enable one to place the meal in the 
oven at their convenience, setting the clock and thermostat with the 
knowledge that the energy will be turned on at the proper time and 
continue until the oven is of the desired temperature, then the ther- 
mostat will stop the current flow and the meal will be prepared by 
the fireless cooker method at the proper time. 

Five principal reasons have been paramount in the delay of the 
general public in taking up electric cooking. 

They may be enumerated as follows : 

1. High first cost including purchase price and installation. 

2. Anticipated high operating cost. 

3. Satisfaction with present method of cooking. 

4. Loss in disposition of old equipment. 

5. Slightly longer time for cooking. 

All these reasons are rapidly being overcome. Central sta- 
tions are doing their utmost to cheapen installations by introducing 
low prices and deferred payments. 

POINTS TO BE CONSIDERED IN SELECTING AN 
ELECTRIC RANGE 

The desirable characteristics as developed during the tests are 
indicated below. Most of the ranges tested met these requirements 
very well. 

In general an electric range should be : 
Attractive in appearance; 
Easy to clean ; 
Provided with heating units separately controlled. 

Surface burners should have : 
Porcelain heating units ; 
Heating units of diflferent sizes. 

The oven should be : 
Quick heating ; 
Ventilated ; 

Of convenient height and size; 
Designed to give uniform browning of foods. 

The heating elements should be easily removable for repairs 
or cleaning. The moulded porcelain types of coils are desirable as 
they heat quickly and one can tell readily when the current is on. 
Open coils are best for the oven. 

Surface or hot plate elements of different diameters are de- 
sirable. Such elements accommodate cooking vessels of different 
sizes and thus save much energy. 

The oven should be non-rusting, well insulated, and provided 
with a substantial, close-fitting door. The steam tight oven is not 



36 

desirable because food will not brown until extra energy is used to 
eliminate the moisture. 

Ovens raised from the floor are more convenient. The glass 
door is more economical, because there is less necessity for opening 
the door, resulting in loss of heat. The glass is, however, liable 
to be broken when hot, by a little cool air striking it. Pyrex glass 
used in the door would probably remedy this defect. 




Fig. 31. Range No. 5. Heating units enclosed type. 



A right hand oven with a door that opens down is most conven- 
ient. 

The oven should have a dependable thermometer or temperature 
indicator. 

Each element should be individually fused and should have a 
separate switch. This would prevent the whole or a large portion 
of the stove being rendered inoperative by accident to a single unit. 

Ample capacity in burners is to be desired, so that delays may 
be reduced to a minimum. 

The inside dimensions of the oven should be about eighteen 
inches wide, twelve inches high, and sixteen inches deep. 



DESCRIPTION OF RANGES 

The size of the oven as stated represents the size of the largest 
receptacle it will accommodate and not the outer dimensions given by 
some of the manufacturers. 

The four surface burners of range No. i are of open construc- 
tion and of different diameters. The oven is eighteen and one-half 




Fig. 32. Range No. 6. 



Surface burners, porcelain type, 
porcelain and open type. 



Oven heating units, 



inches wide, ten inches high, and eighteen inches deep, with two large 
open heating units, each taking 1200 watts. The oven is ventilated. 



38 

There is no heat insulation between the bottom of oven and warm- 
er oven which is just below. The door does not fit tightly and opens 
downward. There is a metal thermometer in the door. 

Range No. 2 has three surface burners of moulded porcelain of 
the same diameters. The oven is eighteen inches wide, fourteen 
inches high and twelve inches deep, with two large open heating 
units, each consuming 1250 watts. The oven is well insulated and 
ventilated. The door fits tightly and opens downward. There is a 
metal thermometer in the door. 

The two surface burners of Range No. 3 are enclosed, both 
being eight and one-half inches in diameter. The oven is nineteen 
inches wide, ten and one-half inches high and twelve inches deep, 
provided with two large open heating units using 1000 watts each. 
It is well insulated and ventilated. The door, with glass panels, opens 
from the side. The oven is equipped with a metal temperature in- 
dicator and automatic clock current control. 

Range No. 4 has four surface burners of open porcelain. Three 
are six and one-half inches in diameter, one eight and one-half inch- 
es in diameter. The oven is eighteen and one-half inches wide, 
fifteen inches high and twelve inchest deep, with two large heating 
elements. The upper one is open and the lower one enclosed, both 
together taking 2500 watts. The oven is not ventilated. The door 
is poorly fitted and opens downward. There is a metal thermometer 
in the door. 

The surface burners of range No. 5 are enclosed, one eight 
inches in diameter and three, six inches in diameter. The oven is 
eighteen inches wide, twelve inches high, and eighteen inches deep, 
with two large enclosed heating units, taking 3500 watts total. The 
oven is well insulated but not ventilated. There is a mercury ther- 
mometer in the door. 

Range No. 6 has three surface burners of the open type. One 
is nine inches in diameter, the other two, seven and one-half inches 
in diameter. The oven is fifteen inches wide, thirteen inches high 
and eighteen and one-half inches deep, with two large heating units, 
taking 1000 watts each. The upper heating unit is of open construc- 
tion, the lower, porcelain construction. The oven is ventilated, and 
equipped with a metal thermometer and automatic clock current con- 
trol. The door fits tightly and opens from side. 

Range No. 7 has three surface burners that are of the semi-en- 
closed type. One is six inches in diameter, — the other two are eight 
inches in diameter. The oven is eighteen inches wide, ten inches 
high and seventeen inches deep, with an open type upper heating unit 
and enclose lower unit, each using 1250 watts. It is well insulated 
and ventilated. The door fits well and opens downward. There is 
a metal thermometer in the door. 



39 




Fig. 



33. Range No. 7. Surface burners semi-enclosed type. Oven heating units, 
enclosed and open type. 



40 

CONCLUSIONS 

The modern electric range has improved ventilation, resulting 
in more efficient application of heat. The surplus moisture is car- 
ried off and but little heat escapes. Meat, bread, cakes, and pies 
brown evenly to any degree on top, bottom and sides. 

There is no need of matches. 

There are no odors from gas or smoke. The kitchen is not hot. 

There is no fire to use up the air in the room. 

There is no scouring of pots and pans, so much time and labor 
are saved. 

The electric oven is always ready and does its work with econ- 
omy, cleanliness and little supervision. 

The main obstacle which tends to restrict the use of electric 
ranges seems to be their price and the high rate of electric energy. 
If the rates were lowered, so that the operating expense would be 
the same as for other fuels, the added advantages of more leisure 
time, less labor and clean, sanitary methods would be obvious. 
These advantages should be taken into account when considering 
electric ranges, together with the fact that the insurance rate is 
usually reduced where gas is not taken into the home. 

Statistics* show that there are more homes in the United States 
already which are supplied with electric current, than are supplied 
with running water. Thus it seems that further publicity and the 
introduction of special cooking rates will bring about the general use 
of electricity for cooking purposes. 

The electric range is just beginning to receive the recognition 
which it deserves, being superior both to the coal and the gas range. 
A far higher percentage of the heat energy is absorbed by the food 
in the cooking and baking operations and very little goes into the 
kitchen to make it uncomfortably warm in hot weather. 

The uniform results that can be obtained with the electric oven 
and the hot plates are appreciated by those who have used both gas 
and electric ranges. 

* Encyclopedia Britannica 



INDEX 

Page 

Advantages of electric ranges - - - 33 

Baking tests 16 

biscuits - 17 

bread 17 

cake 17 

meat 17 

Baking curves discussion 17 

Baking costs 28 

biscuits 28 

bread 29 

cake A 29 

meat - 29 

Biscuit baking, test 17 

cost • 28 

Bread baking, test 17 

cost - 29 

Cake baking, test 17 

cost - -- 29 

Characteristics of range loads 32 

Conclusions 40 

Cooking of foods, purpose 6 

Cooking curves, discussion, oven 17 

Cost of baking 28 

Curve discussions 17 

baking -17 

heat insulation of oven 14 

open door 13 

preheating ovens empty 13 

preheating ovens filled 13 

surface burner 24 

temperature indicator 14 

Efficiencies of, ovens 15 

surface burner 25 

Insulation of oven, test 14 

Introduction 5 

Meat baking, test 17 

cost 29 

Observations, miscellaneous 22 



INDEX 

Page 

Open door, test 11 

discussion of curves 13 

Oven, efficiencies 15 

lieat insulation 14 

tests 9 

Preface - 4 

Preheating, ovens empty, test 10 

ovens filled, test 11 

discussion 13 

Ranges, data 30 

description 37 

desirable characteristics ^ 35 

load characteristics 32 

selecting 35 

tested .- : I. 9 

Surface burners 22 

description 22 

discussion 23 

efficiencies 25 

tests 24 

Temperature indicators ;... 14 

Testing, baking 16 

efficiencies of oven 15 

efficiencies of surface burner 25 

heat insulation of oven walls 13 

open door testing of ovens -.. 11 

ovens 9 

preheating ovens empty -- 10 

preheating ovens filled 11 

surface burners 24 



%- 



